High-performance microring resonator enhanced Ge-on-Si single photon avalanche diode

Waveguide-coupled germanium-on-silicon photodetectors have garnered significant attention due to the sensitive infrared response of germanium and compatibility with CMOS technology, widely employed in high-density and large-scale integrated optoelectronic products. These inherent advantages have also led to the huge interest in germanium-on-silicon single photon diodes. In this paper, we present the design of a microring resonator enhanced germanium-on-silicon single photon avalanche diode. The microring resonator is designed to enhance the light absorption in germanium absorption region through resonant enhancement. Moreover, a three-terminals structure is implemented to mitigate the dark count rate. And by optimizing the doping concentration and width of the doping region, the electric field at the silicon-germanium interface is effectively suppressed, resulting in a significant reduction in dark current. We employ a 2D Monte Carlo simulator to obtain the photon detection efficiency. This microring resonator enhanced single photon avalanche diode demonstrates twice the photon detection efficiency compared to the same size straight waveguide detector. In conclusion, our designed detector exhibits higher detection efficiency and lower dark current compared to conventional devices. These results illustrate clear potential for integration with Si photonics for on-chip applications.